The 50-year hunt: How 2013’s Nobel laureates in Physics found the Higgs boson

For a long time, classical physics was doing just fine. With its now simple-seeming equations and quaint assumptions that physics must behave rationally at every level, it seemed destined to be king and the source of some future grand unified theory. Quantum physicists were a minor annoyance, a crackpot fringe that didn’t command much funding or acclaim, so their objections weren’t overly worrying.

No, the model that Newton had defined was doing very well until objections to the underlying physics started coming from within the movement. During the 50’s and 60’s, physicists with no ghastly allegiance to any upstart models began to sheepishly raise concerns — most importantly, that the math predicted a number of new particles.

One of the most glaring issues was that detailed mathematical work had determined that certain known particles ought to be massless, despite the fact that their masses were known and easy to confirm. Neither could be refuted, the math or the measurements, and so the theory adapted. It accommodated the new requirements for physics by postulating the existence of any hypothetical particle that would allow them. With respect to massless particles, the physicists postulated a field that would imbue inherently massless particles with precisely the masses we observe in the world. This eventually became known as the Higgs field, after one of its main proponents, so the unit which produced that field naturally became the Higgs boson.

Peter Higgs in 2008.

This year’s Nobel Prize in Physics was awarded to Peter Higgs and François Englert for their work in predicting the existence and properties of the Higgs boson. It’s a shame that only three people can be named to a Nobel Prize, since dozens deserve mention in this quest, but perhaps it’s best to put a cap on that sort of recognition.

A boson is a type of elementary particle, and the Higgs boson is a particularly elusive type. Though the math could be worked out with painstaking care, actually observing the Higgs would be something else altogether. For decades scientists became more and more sure of its existence, primarily because acting as though the Higgs was there allowed some truly impressive predictions. A Higgs-containing model predicted the existence of the top quark, for instance, a prediction that, its proponents claimed, no Higgs-less universe could accommodate.

Still, that’s only indirect evidence, strong but ultimately too weak to matter. Direct evidence would be necessary to truly close the issue, but the very math that predicted the existence of the Higgs also predicted that it would be impossible to observe; it was fundamentally not the sort of thing that could just be measured as it sits beyond our puny powers of three-dimensional observation. The particle would only become visible to us as part of an immense event, something powerful enough to knock it down into our universe long enough for scientists to spy it. After several propositions and many, many years spent campaigning, a multinational team built the Large Hadron Collider (LHC), which in 2008 had its inaugural run.

The LHC was almost 30 kilometers around and sported the most advanced technology ever devised by man; the math predicted it and the public’s enthusiasm was behind them, and so the LHC booted up with great expectations. Scientific and political careers rested on a validation of the collider’s roughly $9 billion price tag — but it didn’t come quickly.

Proof!

The discovery of the Higgs was a bit of an emotional roller-coaster for the physics community, which went into the experiment all but unanimous in the expectation that the LHC would produce a quick and perfect proof of the particle. Instead, it performed below expectations and even sprung an explosive coolant leak that shut it down for some time. Even when operational and operating at full capacity, the LHC did not seem to be producing the expected results. It kept smashing the particles, but no Higgs bosons were to be found. At the experiment’s lowest point, reporters began asking them questions like “After this many runs, how likely is it the boson could actually be there?”

In 2011, CERN scientists reported that they were 95% confident there was no particle like the Higgs boson within their given mass range — but their mass range was huge, from 145 to 466 giga-electron-volts (GeV). Though disappointing, the LHC results did allow scientists to narrow the range of their search — and when narrowing their search to the area of just 115 to 130 GeV, they were able to look much more carefully. Here, finally, they began to see signs of the Higgs. Because it was such a sensitive topic in the news, the results were kept strictly private until they could be confirmed.

Throughout 2012 CERN continued to release decreasingly nervous updates about the state of the evidence, removing caveats and strengthening language as the evidence continued to pile up. Eventually they called it: the Higgs boson had been found.

To this day it’s unknown if there might in fact be more than one type of Higgs boson, or whether its most nuanced characteristics will diverge from predictions. Still, the Higgs is a largely finished chapter in physics, at least for now, as the LHC moves on to other projects. The graviton is the natural successor to the Higgs in terms of a new scientific target, an as-yet-unproven particle that uses the effect of the Higgs boson (mass) to exert force (gravity). If confirmed, that will help to bridge the gap between classical and quantum physics, further uniting the two great tribes in modern physics and chemistry.